Question

[8 MARKS] Question 3 Assume a bank account begins with a balance of R100 and earns interest at an annual rate of 5%. The interest is computed at the end of each year using the following formula previousBalance + (1 + interestRate); newBalance %3D You have to write three java classes named ComputeInterest to compute and display this account balance at the end of a five-year period. You only have to write the code. Each different verSion must make use of a different type of loop (2) Give all the necessary variable declarations and initialısatıons. Use a while loop 31 (2) (2) 3.2 Use a do loop 3.3 (2) Use a for loop 3.4

Answer 1

Use a while loop 
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
//Class for compound interest
class ComputeInterest {
    //variables
    private int newBalance;
    private double interestRate;
    //Constructor
    ComputeInterest(int newBalance, double interestRate){
        this.newBalance = newBalance;
        this.interestRate = interestRate;
    }
    //Getter and setter
    public int getNewBalance() {
        return newBalance;
    }

    public void setNewBalance(int newBalance) {
        this.newBalance = newBalance;
    }

    public double getInterestRate() {
        return interestRate;
    }

    public void setInterestRate(double interestRate) {
        this.interestRate = interestRate;
    }
    //Find balance after n years 
    public double getBalance(int n){
        double ans = newBalance;
        while(n-->0){
            ans = ans*(1+interestRate/100);
        }
        return ans;
    }

    public static void main(String[] args) {
        ComputeInterest c = new ComputeInterest(100,5);
        System.out.println("Balance after 5 years: "+c.getBalance(5));
    }
}

Use a do while loop :

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
//Class for compound interest
class ComputeInterest {
    //variables
    private int newBalance;
    private double interestRate;
    //Constructor
    ComputeInterest(int newBalance, double interestRate){
        this.newBalance = newBalance;
        this.interestRate = interestRate;
    }
    //Getter and setter
    public int getNewBalance() {
        return newBalance;
    }

    public void setNewBalance(int newBalance) {
        this.newBalance = newBalance;
    }

    public double getInterestRate() {
        return interestRate;
    }

    public void setInterestRate(double interestRate) {
        this.interestRate = interestRate;
    }
    //Find balance after n years
    public double getBalance(int n){
        double ans = newBalance;
        n--;
        do{
            ans = ans*(1+interestRate/100);
        }while(n-->0);
        return ans;
    }

    public static void main(String[] args) {
        ComputeInterest c = new ComputeInterest(100,5);
        System.out.println("Balance after 5 years: "+c.getBalance(5));
    }
}

Using a for loop :

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
//Class for compound interest
class ComputeInterest {
    //variables
    private int newBalance;
    private double interestRate;
    //Constructor
    ComputeInterest(int newBalance, double interestRate){
        this.newBalance = newBalance;
        this.interestRate = interestRate;
    }
    //Getter and setter
    public int getNewBalance() {
        return newBalance;
    }

    public void setNewBalance(int newBalance) {
        this.newBalance = newBalance;
    }

    public double getInterestRate() {
        return interestRate;
    }

    public void setInterestRate(double interestRate) {
        this.interestRate = interestRate;
    }
    //Find balance after n years
    public double getBalance(int n){
        double ans = newBalance;
        for(int i=0;i<n;i++){
            ans = ans*(1+interestRate/100);
        }
        return ans;
    }

    public static void main(String[] args) {
        ComputeInterest c = new ComputeInterest(100,5);
        System.out.println("Balance after 5 years: "+c.getBalance(5));
    }
}

OUTPUT :

Computelnterest getBalance Run: Computelnterest X "C:\Program Files\Java\jdk-13\bin\java.exe" "- Balance after 5 years: 127.62815625000002 Process finished with exit code 0